import java.util.HashMap;
import java.util.Map;

public class TestHashMap {
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Map<Object, Object> m = new HashMap<Object, Object>();
		m.put(null, 1);
		m.put(null, 2);
		System.out.println(m.get(null));
		System.out.println(m.size());
	}
}
